1. Technical Field
The present invention relates to projective displays and, more particularly, to a projective display implementing an operational principle where a conventional projector operates upon to project an image presented at a liquid crystal display to a projection surface.
2. Description of Related Art
The promptly developed display technology revolutionizes projective systems and other displaying devices. The operational mechanisms where conventional projectors operate upon can be generally divided into three types, which are cathode ray tube (CRT), transparent liquid crystal display (LCD) and digital light processor (DLP). Especially, transparent LCD is popular among business people for the advantageous lightweight and portability thereof.
Projective methods applied to projectors using transparent LCD can be further divided into two types. The first one is to make a light source pierce through a single LCD, and then be filtered by a color filter so as to derive a true-color image for being projected onto a specific projection surface. The other method is to resolve a light into red, green, and blue color-channels, namely RGB colors, and make the color channels pierce through a respective LCD. Afterward, the three color-channels are again integrated into a colored image for being magnified and projected onto a specific projection surface.
Since projectors employing the aforementioned two projective methods are far superior to those employing CRT as the operational mechanism in both image quality and compact volume, they are extensively adopted in offices, classrooms and families.
FIG. 1 depicts a projector 10, which uses transparent LCD as previously described. While it is advantageous by the portable volume and weight, it still requires to be signally connected with an electronic device, e.g. a personal computer, for receiving image signals from the electronic device, so as to project an image provided by the electronic device onto a specific projection surface, just like projectors employing CRT as the operational mechanism. However, for purpose of the aforementioned signal connection, time can be significantly consumed and hardware conflicts may occur between devices from different manufacturers. Besides, to users who frequently use such conventional projectors to facilitate their briefing or presentation, it is undoubtedly a burden to bring laptops and projectors simultaneously. Some prior arts have attempted to remedy these problems by integrating a personal computer with the projector 10, such as Taiwan Patent Publication M268621, entitled as “Projective Notebook”. Nevertheless, such solution somehow sacrifices convenient usage that a personal computer originally performs.
Hence, a need exists for perfectly integrating a projection function with displays of various existing electronic devices so that a user can optionally make an image magnified and projected onto a specific projection surface as needed, or the user can directly view the image provided by the electronic device through the display.